Hives

Also known as urticaria, hives are itchy, raised and swollen red bumps (weals) that appear on your skin. They can pop up anywhere on your body, including your ears, face, lips, throat and tongue. They vary in size from a few millimetres to the size of a dinner plate. Several weals can merge together to form larger patches called plaques. They may go away in a few hours or last for a few weeks.

Hives are a reaction to histamine, a chemical released by your body as part of the immune response.

They’re more common in children, women aged 30-60 and anyone who’s susceptible to allergies.

Hives are classed as either:

• Acute — when they last for fewer than six weeks
• Chronic (long-term) — when they last for longer than six weeks

You may have:

• Itching, burning or stinging
• Raised, round or oval-shaped weals
• Red or flesh-coloured weals

Hives are usually harmless but sometimes they can be the first symptom of anaphylaxis, a potentially life-threatening allergic reaction. Other symptoms of anaphylaxis include:

• Collapse and loss of consciousness
• Difficulty swallowing 
• Feeling faint or dizzy
• Swollen eyelids, lips, hands and feet
• Tummy pain, nausea and vomiting
• Wheezing and breathing difficulties

You may also have an increased heart rate. Call 999 if you think you or someone else has anaphylaxis.

Hives will probably go away in 48 hours. However, if your hives persist after this time, you should see your GP. 

You should also see your GP if:

• You have other symptoms in addition to your hives eg a fever or feeling unwell
• You have swelling under your skin (angioedema) — angioedema is similar to hives but symptoms typically include swelling around the eyes and lips, and sometimes the feet, genitals and hands; angioedema can last longer than hives but still usually goes away in 24 hours; in rare cases, angioedema can be life-threatening when swelling of the airways, lungs, throat or tongue makes breathing difficult
• Your hives are causing you distress
• Your hives are severe
• Your hives keep recurring
• Your rash is spreading 

You should also see your GP if you’re concerned about your child’s hives. 

Your GP will examine your rash and ask about any other symptoms to help determine what’s causing it. They may ask you further questions about your symptoms such as:

• When did your symptoms start?
• Does anything make your symptoms better or worse? 
• Do you have tightness in your chest or throat, difficulty breathing or nausea?

They may also ask questions about your family history, lifestyle and recent experiences, such as: 

• Do you have a family history of hives or angioedema?
• Have you recently had a bacterial or viral infection?
• Have you recently travelled to a new place?
• Have you recently tried any new foods?
• What medications, herbal remedies and supplements do you take?

Your GP may ask you to keep a diary to track: 

• Medications, herbal remedies and supplements you're taking
• What you're eating and drinking
• Where your hives appear and how long they take to fade
• Whether your hives occur alongside painful swelling
• Your activities

If your GP suspects your hives are caused by an underlying condition, they may arrange further investigations, such as blood tests or skin tests.

Acute hives

Tests are often not necessary but sometimes your GP may refer you to an allergy clinic.

Chronic hives

You may be referred for the following tests:

• A stool sample to detect parasites in your intestines
• Blood tests for thyroid conditions, immune system disorders and liver function

Hives occur when blood plasma leaks out of blood vessels in your skin. This happens in response to histamine released by cells along these blood vessels. Certain triggers cause histamine and other chemicals to build up causing hives. 

Acute hives

In many cases, it isn't possible to discover what triggered hives. However, the most common cause of hives is an allergy. Common allergy triggers include:

• Dust mites, insect bites and stings 
• Foods such as cheese, chocolate, eggs, fish, fresh berries, milk, nuts, shellfish and tomatoes — fresh foods cause hives more often than cooked foods and some food additives and preservatives can also cause hives
• Latex and chemicals
• Medications — this includes: 
• Antibiotics
• High blood pressure medication eg ACE inhibitors
• Non-steroidal anti-inflammatory drugs (NSAIDs) eg ibuprofen
• Painkillers eg aspirin or codeine
• Pet dander (skin)
• Pollen

Non-allergy triggers include:

• Emotional stress
• Exercise
• Physical triggers such as skin pressure, temperature changes, friction and even the sun and water
• Viral infections

Chronic hives

Chronic hives last more than six weeks and in most cases, the cause remains unknown. However, in some cases it may be caused by: 

• An autoimmune disease, when your immune system attacks its own body
• An underactive or overactive thyroid gland
• Cancer
• Infection — this includes: 
• Parasites in your intestines
• Viral hepatitis (liver disease)

You may find that these triggers make hives worse or come back:

• Alcohol
• Caffeine
• Certain food additives
• Certain medications
• Physical triggers
• Stress

You may not need any treatment because hives often clear up in a couple of days. In the meantime, it’s best if you avoid any triggers you know you have.

Treatments include a short course of corticosteroids, which suppress your immune system, menthol cream to soothe itching and/or antihistamines.

Antihistamines block the effects of histamine, the chemical that causes the weals and itching. However, they may not be suitable for young children or if you have a long-term medical condition, so speak to your pharmacist before trying them.

Non-drowsy antihistamines are usually recommended as they do not have many side effects. If the initial dose prescribed isn't effective, your doctor may increase the dose. If non-drowsy antihistamines aren't effective, your doctor may suggest other antihistamines, which can make you drowsy and should be taken at bedtime.

If antihistamines are not effective, your doctor may prescribe:

• Anti-inflammatory drugs
• Asthma drugs taken alongside antihistamines
• Histamine (H-2) blockers
• Immune-suppressing drugs
• Man-made (monoclonal) antibodies

If you have chronic hives your doctor may also refer you to a dermatologist, a doctor specialising in skin conditions. They may suggest stronger antihistamines or other medicines to suppress your immune system, such as ciclosporin and omalizumab.

Chronic hives can last for months or years and disturb your sleep, as well as interfere with work and other activities. You can ease your symptoms or help prevent your hives recurring by avoiding: 

• Known triggers
• Scratching 
• Using harsh soaps

It can also help to: 

• Apply sunscreen before you go outside
• Soothe the affected skin by:
• Applying a cool cloth
• Applying an unscented lotion or anti-itch cream
• Having a bath
• Using fan
• Wear loose, light clothing
• Keep a diary of when and where your hives occur, as well as what you were doing, drinking or eating at the time — this can help identify what triggers your hives.